Hot ductility and strength of SiC{sub p}/A356 Al composite and matrix alloy by torsion testing

Conference · Fri Dec 31 04:00:00 EST 1993

OSTI ID:143685

McQueen, H J; Sakaris, P; Bowles, J ^[1]

---

1. Concordia Univ., Montreal, Quebec (Canada)

Torsion testing was conducted on a metal-matrix composite (MMC, 15 v% SiC{sub p}A356 Al) and its matrix alloy over the range 300 to 540{degree}C and 0.1 to 5.0 s{sup {minus}1}. Comparison of flow stress ductility and other hot working parameters is presented. Flow stresses of the A356 MMC were found to be generally higher than A356 alloy but the difference was quite small at higher temperatures. Flow stresses were found to depend on the strain rate through a sinh function and on temperature through an Arrhenius term with activation energies of 263 kJ/mol for the composite and 161 kJ/mol for the matrix; the increased value for the composite suggests that the SiC particles force the matrix to undergo additional strain hardening. Dynamic recovery seems to be predominant in A356; however, dynamic recrystallization likely nucleates in the vicinity of silicon carbide particles in 15 v% SiC{sub p}/A356 Al. Ductility of the composite, about 25% below that of the alloy, rose by a factor of 4 between 400 and 500{degree}C to become higher than many wrought alloy composites. The low ductility of A356 was shown to result from linking up of the cracks nucleated at Si particles, whereas linkage of the decohesion voids at the SiC was associated with more plastic flow in the matrix which had much finer Si particles than the bulk alloy.

• OSTI ID: 143685
• Report Number(s): CONF-930246--; ISBN 0-87339-251-5
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
COMPOSITE MATERIALS
DUCTILITY
SILICON CARBIDES
STRESS ANALYSIS
TENSILE PROPERTIES